Rotary or drum-type cutting dies are commonly used for producing a container or carton blank from corrugated board sheet material. Such rotary dies are typically comprised of a pair of cooperating cylinders or drums. One of the cylinders, a cutting cylinder, includes a die board having cutting blades or rules while the other, the anvil cylinder, provides a backing surface against which the cut is made.
Rotary cutting dies of the type described above are often employed to produce slots or various shaped openings in the blank sheet of corrugated board material that is being processed. As such, provisions for removing or stripping the severed scrap material from certain cutting blades and the processed blank must be provided. Otherwise, if not actively removed from the vicinity of the cutting die, the scrap material tends to collect around the cutting blades and, render the rotary cutting die inoperable.
Equally important, with regard to the stripping or ejection of scrap material, is the direction in which the successfully stripped or ejected scrap exits the cutting die apparatus. As the usable product of the cutting process is typically expelled directly outward from the nip of the rotary cutting die apparatus, it is desirable, in order to obtain complete separation of scrap and corrugated board product, that the scrap be ejected from the rotating cylinders at a significantly different trajectory than the corrugated board product.
In the past, resilient rubber strips or pads made of closed cell, high density foam or gum rubber have been placed adjacent the cutting blade so as to forcibly eject the corrugated board scrap material. However, previous resilient strippers have suffered from a number of shortcomings, particularly with regard to directional control of the ejected scrap material. First, it should be noted that scrap strippers of the prior art do not typically extend substantially past adjacently disposed scrap cutting blades even when in a non-compressed posture. Thus, while these scrap strippers may possess enough resiliency and strength to strip cut scrap pieces from the adjacent blades, they do not have the ability to significantly play a major role in controlling the direction and flight of scrap pieces exiting the nip between the rotating cutting die and the anvil. Thus, one typically finds cut scrap flying outwardly and sometimes upwardly out of the nip. The net result is that the scrap becomes airborne and intermingled with the exiting corrugated board product and ultimately becomes packaged with the supposedly clean product. Obviously, scrap intermixed with the final corrugated product is most undesirable, especially in certain industries and certain cases such as with pizza containers, for example.
Therefore, it has been found that conventional scrap strippers are incapable of extending or achieving a height that enables them to exercise control over the flight or trajectory of the exiting scrap pieces. Again, this is because in typical applications, the relatively hard rubber stripper pads when expanded (non-compressed) just barely extends in height past the adjacent scrap blade or blades and, as such, they cannot, in reality, significantly affect the flight path of the scrap pieces exiting the nip.
Therefore, there remains a need for a practical, reliable, and cost effective resilient scrap stripping member for use with corrugated board rotary cutting dies which efficiently separates severed scrap material from an associated blank of corrugated board material and which furthermore provides control of the ejected or stripped scrap trajectory as it exits the rotary cutting die apparatus.